# Particle Physics Masterclass 2012

The second lecture was given by Professor Bill Scott on the fundamentals of particle physics.

There are 12 fundamental matter particles and 12 forces. Gravity is ignored as it is so weak.

The professor summarised the basic parts of the atom. The positive proton has a mass equivalent of 938.3 MeV, the neutral neutron has a mass equivalent of 938.3 MeV and the negative electron has a mass equivalent of 0.511 MeV (t There are 12 fundamental matter particles and 12 forces. Gravity is ignored as it is so weak.

The electron is a fundamental particle).

He then continued by describing Heisenberg’s uncertainty principle. The probability of finding a particle is the “wave”. You either know the position of the particle or know its momentum (and vice versa. You can’t know both. This is the uncertainty.

Nucleons are composites of quarks. Quarks move very fast where the wave of the particle comes from kinetic energy. Photons (particles of em radiation) are responsible for transferring electrical and magnetic forces. Explained by photon exchange and Feynman diagrams are used to illustrate the processes.

The “weak” force is involved in beta decay. N –> p+ + e + νbar

DESY lab in Hamburg. A struck quark forms a “jet” of “mesons”.

Quarks and gluons are said to be “confined” in hadrons. A meson is a composite particle made up of a quark and antiquark.

Pulling quarks apart far enough breaks the inverse square law.

Gluons can bounce of other gluons. Gluons are not really coloured. The colour names are just used to differentiate them.

A free neutron is unstable. A down quark (d) in a neutron is changed into an up (u) quark. So far the proton hasn’t been seen to decay.

An antiparticle can be thought of as a particle going back in time.

The Higgs field is scalar.

Zo boson can decay to an electron and positron. A Z boson can also decay to a larger particle.

Fermions are matter particles.

Ambient Higgs field behaves like a ferromagnet.

The LHC is needed to discover the Higgs.